Namespace all wpilibc functions/classes into "frc" namespace. (#311)

Base.h provides a backwards compatibility shim (enabled unless
NAMESPACED_WPILIB is defined) that does a "using namespace frc".
However, as some header files do not include Base.h, this may
be a breaking change in some corner cases (with an easy fix).

Fixes #218.

wpilibc/shared/include/SmartDashboard/SmartDashboard.h

@@ -17,6 +17,8 @@
 #include "SmartDashboard/Sendable.h"
 #include "tables/ITable.h"
 
+namespace frc {
+
 class SmartDashboard : public SensorBase {
  public:
   static void init();
@@ -94,3 +96,5 @@ class SmartDashboard : public SensorBase {
    */
   static std::map<std::shared_ptr<ITable>, Sendable*> m_tablesToData;
 };
+
+}  // namespace frc